RFBL Flanges
Blind flanges, also called blanking flanges or RFBL (raised face blind) flanges, are solid flanges with no bore. They are bolted onto the end of a pipe, valve or vessel opening to close it off, which makes them one of the most useful parts of any piping system. We hold blind flanges to EN1092-1 and ANSI B16.5, in A182 F304/L and F316/L, so you can find the right fit for your system.
RFBL Flanges
What is a blind (RFBL) flange and how does it work?
RFBL stands for raised face blind. The raised face is the part of the flange that seats the gasket, and blind means there is no bore, so the flange is a solid disc that seals the end of a line.
A blind flange has the same bolt hole pattern as the flange it closes, so the two line up. You bolt them together with a gasket between them. As you tighten the bolts, the gasket is squeezed between the two raised faces, and that is what makes the seal. Apart from having no bore, a blind flange is made to the same thickness and drilling as other flanges of its size and rating.
Where are blind flanges used?
The common uses of a blind flange include shutting off sections of pipe, high-pressure applications, and testing the flow of gas or liquid through a pipe. They’re also used to isolate a line for maintenance.
Because they’re bolted rather than welded, they give easy access for inspection, cleaning or a future extension of the system. That’s why you’ll often see them on the ends of pipe runs and on vessel openings.
What should you check before ordering a blind flange?
A blind flange needs to match the flange it’s closing. Check the standard, the rating and the face before you order.
Our EN1092-1 blind flanges, made to the European flange standard, are held in the PN (nominal pressure) ratings shown in each listing. Our ANSI B16.5 blind flanges, made to the American standard, come at 150LB and 300LB. If you’d like to see the wider choice, you can browse our EN1092-1 flanges or our ANSI B16.5 flanges, depending on which standard your existing flange follows.
Which flanges do blind flanges pair with?
A blind flange is bolted to the flange on the end of the line it closes. These are the three flange types we most often match them to:
RFSO flanges, or raised face slip-on flanges, which slide over the pipe and are welded in place. They’re a straightforward choice for general pipework at moderate pressures.
RFWN flanges, or raised face weld neck flanges, which have a tapered neck that is welded to the pipe. They make a stronger joint, so they’re used where pressures or temperatures are higher.
RFSO bored O/D flanges, which are slip-on flanges bored to fit the outside diameter of hygienic or metric tube instead of standard pipe.
Whichever flange you’re closing, choose a blind flange in the same grade, either 304 or 316.
What are the common ordering mistakes?
The most common mistake is mismatching the rating, such as a PN16 blind against a PN40 flange or a 150LB blind against a 300LB flange. A blind rated lower than the flange it closes can’t hold the same pressure, and the thickness or drilling may not match either. The second is mixing EN1092-1 and ANSI B16.5. The two standards use different drilling, so the bolt holes won’t line up even when the pipe size looks the same.
The third is overlooking the face. The blind has to suit the face of the flange it closes, so a raised face blind needs a raised face flange to seat the gasket properly. Checking all three before you order saves time and avoids a return.
What should you tell us when you enquire?
A blind flange has to match the flange it closes, so please tell us:
1. The size, either as a DN or NPS size.
2. The standard and rating of the flange you need to close, such as EN1092-1 PN16 or ANSI B16.5 150LB.
3. Whether the flange you’re closing has a raised face, because our blind flanges are raised face.
4. The grade, either 304 or 316.
5. How many you need.
Please check the markings on the flange you’re closing first.
Frequently asked questions
How do I choose the size of a blind flange?
A blind flange closes the end of a line, so it has to match the flange on that end. Choose the same size, rating and face as that flange, and let us know if you’re not sure what they are.
Do blind flanges need a gasket?
Yes. Like any bolted flange joint, a blind flange needs a gasket between the faces, plus bolts and nuts. Check these suit your rating and face before you order.
Which grade should my blind flange be?
Match it to the rest of your system. The inner face of a blind flange sits against whatever is in the pipe, so use 316 where the line needs extra corrosion resistance, and 304 for milder duties.
Contact Anglo Stainless for more information
If you’re not sure which blind flange you need, contact us with the size, rating and face of the flange you want to close off, and a member of our team will be happy to help. You can also request our brochure using the form below.
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DN600 EN1092-1 PN40/05B RFBL A182 F316/L
24″ ANSI B16.5 300LB RFBL A182 F316/L24″ ANSI B16.5 300LB RFBL A182 F304/LDN500 EN1092-1 PN40/05B RFBL A182 F316/L20″ ANSI B16.5 300LB RFBL A182 F316/L20″ ANSI B16.5 300LB RFBL A182 F304/LDN450 EN1092-1 PN40/05B RFBL A182 F316/LWhat is a blind (RFBL) flange and how does it work?
RFBL stands for raised face blind. The raised face is the part of the flange that seats the gasket, and blind means there is no bore, so the flange is a solid disc that seals the end of a line.
A blind flange has the same bolt hole pattern as the flange it closes, so the two line up. You bolt them together with a gasket between them. As you tighten the bolts, the gasket is squeezed between the two raised faces, and that is what makes the seal. Apart from having no bore, a blind flange is made to the same thickness and drilling as other flanges of its size and rating.
Where are blind flanges used?
The common uses of a blind flange include shutting off sections of pipe, high-pressure applications, and testing the flow of gas or liquid through a pipe. They’re also used to isolate a line for maintenance.
Because they’re bolted rather than welded, they give easy access for inspection, cleaning or a future extension of the system. That’s why you’ll often see them on the ends of pipe runs and on vessel openings.
What should you check before ordering a blind flange?
A blind flange needs to match the flange it’s closing. Check the standard, the rating and the face before you order.
Our EN1092-1 blind flanges, made to the European flange standard, are held in the PN (nominal pressure) ratings shown in each listing. Our ANSI B16.5 blind flanges, made to the American standard, come at 150LB and 300LB. If you’d like to see the wider choice, you can browse our EN1092-1 flanges or our ANSI B16.5 flanges, depending on which standard your existing flange follows.
Which flanges do blind flanges pair with?
A blind flange is bolted to the flange on the end of the line it closes. These are the three flange types we most often match them to:
RFSO flanges, or raised face slip-on flanges, which slide over the pipe and are welded in place. They’re a straightforward choice for general pipework at moderate pressures.
RFWN flanges, or raised face weld neck flanges, which have a tapered neck that is welded to the pipe. They make a stronger joint, so they’re used where pressures or temperatures are higher.
RFSO bored O/D flanges, which are slip-on flanges bored to fit the outside diameter of hygienic or metric tube instead of standard pipe.
Whichever flange you’re closing, choose a blind flange in the same grade, either 304 or 316.
What are the common ordering mistakes?
The most common mistake is mismatching the rating, such as a PN16 blind against a PN40 flange or a 150LB blind against a 300LB flange. A blind rated lower than the flange it closes can’t hold the same pressure, and the thickness or drilling may not match either. The second is mixing EN1092-1 and ANSI B16.5. The two standards use different drilling, so the bolt holes won’t line up even when the pipe size looks the same.
The third is overlooking the face. The blind has to suit the face of the flange it closes, so a raised face blind needs a raised face flange to seat the gasket properly. Checking all three before you order saves time and avoids a return.
What should you tell us when you enquire?
A blind flange has to match the flange it closes, so please tell us:
1. The size, either as a DN or NPS size.
2. The standard and rating of the flange you need to close, such as EN1092-1 PN16 or ANSI B16.5 150LB.
3. Whether the flange you’re closing has a raised face, because our blind flanges are raised face.
4. The grade, either 304 or 316.
5. How many you need.
Please check the markings on the flange you’re closing first.
Frequently asked questions
How do I choose the size of a blind flange?
A blind flange closes the end of a line, so it has to match the flange on that end. Choose the same size, rating and face as that flange, and let us know if you’re not sure what they are.
Do blind flanges need a gasket?
Yes. Like any bolted flange joint, a blind flange needs a gasket between the faces, plus bolts and nuts. Check these suit your rating and face before you order.
Which grade should my blind flange be?
Match it to the rest of your system. The inner face of a blind flange sits against whatever is in the pipe, so use 316 where the line needs extra corrosion resistance, and 304 for milder duties.
Contact Anglo Stainless for more information
If you’re not sure which blind flange you need, contact us with the size, rating and face of the flange you want to close off, and a member of our team will be happy to help. You can also request our brochure using the form below.
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